The present invention relates to a side airbag apparatus which inflates and deploys an airbag between a body side portion of a vehicle and a vehicle seat, and cushions a shock from a side portion of the vehicle so as to protect a passenger.
For example, Japanese Laid-Open Patent Publication No. 2004-276808 discloses a side airbag apparatus protecting a passenger from a shock caused by a side collision. The side airbag apparatus is provided with an inflator and an airbag. The airbag is stored in a seat back of a vehicle seat in a state of being folded and made compact.
In the side airbag apparatus, if a shock is applied to the body side portion of the vehicle from a side, the inflator is activated so as to blow out a gas into the airbag. The airbag is inflated and deployed by the blown-out gas, and a specific position of the seat back is broken. The airbag flies out forward from the broken position of the seat back while leaving a part thereof within the seat back. The airbag is inflated and deployed in a narrow passenger restraint region between a passenger seated on a vehicle seat and the body side portion, in the manner mentioned above. Since the inflated and deployed airbag is interposed between the passenger and body side portion, the passenger is restrained and the shock from the side portion is absorbed.
In this case, in a side collision, since the passenger restraint region mentioned above is very narrow in comparison with other types collisions, for example, a front collision, it is necessary to inflate and deploy the airbag in a short period of time immediately after a side collision occurs, in the light of a passenger protection. Accordingly, the airbag is inflated and deployed at a high speed actually at a time of detecting the side collision.
However, in the case of inflating and deploying the airbag at a high speed, since an energy applied to the passenger from the airbag is high, it is hard to reliably restrain the passenger. The problem mentioned above tends to be generated particularly in the case where the passenger is seated on a place which is deviated from a normal position, and a part of the body is positioned in a region in which the airbag is inflated and deployed.